chap 6 integumentary system

organs

• hair

• skin

• nails

layers of skin

• epidermis

• dermis

• hypodermis

protection

• Physical injury, chemicals, microbes, UV radiation, etc.

• Selectively permeable to some chemicals

• functions of skin

prevent water loss

• Water resistant but not completely water-proof

• Perspiration (process of sweating)

• functions of skin

temperature regulation

• Insulation

• Capillary networks

• Sweat glands

• functions of skin

metabolic regulation

• Production of Vitamin D → calcium and phosphate absorption

• function of skin

immune defense

• Epidermal leukocytes

• Immune response (salt and sebum on skin)

• function of skin

sensory reception

• Awareness and response to external conditions

• Tactile cells (Merkel cells)

• function of skin

epidermis

• Keratinized stratified squamous ET

• Avascular – get nutrients from dermis

epidermis strata layers

• stratum corneum (superficial)

• stratum lucidum (thick skin only)

• stratum granulosum

• stratum spinosum

• stratum basale (deep)

stratum basale (deep)

• Single row of cuboidal/columnar cells quickly dividing

• Tightly attached to basement membrane

• cell types

  • keratinocytes

  • melanocytes

  • tactile (merkel) cells

keratinocytes

• epidermal cells that make keratin

• in stratum basale

melanocytes

• secrete melanin pigment

• in stratum basale

stratum spinosum

Several layers of keratinocytes attached by desmosomes

stratum granulosum

3-5 layers of flattened keratinocytes filled with keratin granules

stratum lucidum

• In thick skin only

• 2-3 layers of flat, dead keratinocytes

• Provide extra protection from abrasion in thick skin (palms and soles)

stratum corneum (superficial)

• 20-30 layer of dead keratinocytes

• Plasma membrane filled with keratin

• Protects skin against abrasion, penetration, dehydration, infection, etc

thick skin

• Palms and soles

• 5 strata

• No hair follicles

• might not see hemoglobin and carotene pigment in skin

thin skin

• Most of body

• 4 strata

• Hair follicles

• see hemoglobin (red) and carotene (yellow) pigment in skin

melanin

• in epidermis

• Darkly colored pigment made by melanocytes

• Activated by UV light

hemoglobin

• in dermis

• Oxygen-binding protein in blood

• Bright red when bound to oxygen (makes skin red)

carotene

Yellow pigment in adipose tissue (makes skin yellow)

skin thickness

• thickness depends on shade/color of skin

• hemoglobin, carotene, and melanin combine to make the color of skin

papillary layer

• Areolar CT deep to epidermis

• Dermal papillae interlock with epidermal ridges

• Blood vessels nourish epidermis

• in dermis

reticular layer

• Dense irregular CT

• Make skin resistant to tearing by stretching forces from different directions

• in dermis

hypodermis

• Mainly adipose CT

• Body insulation and cushion

• Highly vascularized (blood vessels)

hair follicle

• Hair is keratinized cells growing from hair follicles

• is made from specialized regions of the epidermis and dermis:

  • Connective tissue root sheath

  • Epithelial tissue root sheath

hair

• Hair matrix is where new hair is produced

  • Surrounds the hair papilla where blood vessels enter

• structure

  • Bulb

  • root

  • shaft

bulb

• swelling at the base

  • Living cells near blood vessels

root

• area of hair imbedded in the skin

  • Dead cells

shaft

• hair that projects above skin’s surface

  • Dead cells

arrector pili muscle

• bundle of smooth muscle that connects to hair follicle

• Hair stands erect when arrector pili contracts (goosebumps)

sebaceous gland

• secrete sebum (oil) into hair follicle

  • Oily substance that lubricates/softens surface of skin and hair

  • Makes skin waterproof

  • Collects dirt

  • Protects from pathogens (acidic pH)

merocrine sweat gland

• produce watery sweat (temperature regulation)

  • Released onto surface of skin (pores)

  • Present on most of the body

apocrine sweat gland

• produce protein-rich (smelly) sweat (release pheromones)

  • Releases into hair follicle

  • Axillary, nipple, anal, and genital areas (attract mates, mother/baby bonding, immune information)

1st degreee burn

• Epidermis

• Heals in 3-5 days

2nd degree burn

• Epidermis & dermis

• Blisters

• Skin heals

3rd degree burn

• Entire thickness of skin

• Burns area is white, red, or black

• Scarring

the rules of nines

• the body surface is divided into areas representing 9% or multiples

• fatality

  • 1. infections

  • 2. dehydration

basal cell carcinoma

• Most common and least dangerous

• Cancer in keratinocytes of stratum basale (divide up)

• Surgically removed

squamous cell carcinoma

• Cancer in keratinocytes of stratum spinosum (don’t divide)

• Early treatment is important

melanoma

• Cancer in melanocytes

• Most fatal type

• Highest rate of metastasis

decubitus ulcer

• area of damaged skin caused by sustained pressure restricting blood flow to the skin.

  • “Pressure ulcer” or “bedsore”

skin aging

• Wrinkles are primarily caused by the natural breakdown of collagen and elastin fibers as you age.

  • Firmness and elasticity are lost over time

  • Exacerbated by UV exposure, facial expressions, and tobacco.

psoriasis

• autoimmune disease that attacks keratinocytes, leading to inflammation and rapid skin cell turnover

  • `Thick, raised, itchy patches of discolored skin covered with scales

  • Treat with immunosuppressant drugs

tactile (Merkel) cells

touch receptors